Really really good art style, and I like how pretty much everything had a countdown timer to match the theme. Love the animations for running and exiting the level, and the movement / gunplay was really solid. Also great boss fight, although in my opinion the boss theme felt a bit disconnected from the goofy music that normally played. I think the countdown timer on the boss that represented its attacks was a great idea.
I think the shooting sound effect was too loud compared to the rest of the volume, and the boss fight theme overlapped with the credits theme. The jetpack didn't really have much of a purpose imo, and the blocks had different hp values but the gun instantly destroyed them which was a bit odd. Outside of those minor issues i think it's a nice short action platformer and you did well for the short time period.